This invention relates generally to the joining together of two members and relates, more particularly to the joining, or bonding, together of items having surfaces which are defined by thermoplastic material.
Conventional methods of joining thermoplastic items, as by welding, involve heat conduction, convection, or radiation and friction, and the heat generated for these methods may be external or internal to the items, or both. For example, the high frequency or dielectric welding of thermoplastics is based on AC-generated waves passing through the plastic sheet or film, causing internal heating through molecular friction, with the subsequent temperature increase of the substrate material. However, this system is limited in that it is only applicable to a substrate with a sufficiently high dielectric loss tangent, i.e. a polymer with active polar groups. For this reason, this technique is usable only for polymers with the aforementioned chemical characteristics.
Other known techniques for welding thermoplastics, most of which involve the softening of areas to be joined to fusion temperature include hot gas welding, hot tool welding, induction welding, spin or friction welding, vibration welding or ultrasonic welding.
It is an object of the present invention to provide a new and improved method for joining together of items, or substrates, comprised of any of a number of types of thermoplastic material.
Another object of the present invention is to provide such a method which accommodates the rapid, low energy joining/bonding of thermoplastic materials.
Still another object of the present invention is to provide such a method which is well-suited for the sealing of printed circuit boards (PCBs) and printed wired boards (PWBs) during the manufacture of these boards.